• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.26-30
• /
• 2005

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result, the stamper surface temperature was controlled according to the desired reference stamper surface temperature.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.2
• /
• pp.100-104
• /
• 2006

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result. the stamper surface temperature was controlled according to the desired reference stamper surface temperature.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.940-944
• /
• 2003

With the increasing demand for plastic micro components, micro-/nano-molding using the mother stamper has received much attention. If the replication temperature is too high, the adhesion between the stamper and the polymer melt may deteriorate the surface quality of the replicated part, excessively wearing down the stamper. In this paper, an experimental method analyzes the temperature dependency of the anti-adhesion property between the actual stamper with patterns of sub-micrometer and the polymer melt. As a practical example, a correlation between the contact angle of the stamper and the surface quality of the molded substrates as a function of the replication temperature, respectively, was obtained quantitatively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.10a
• /
• pp.83-86
• /
• 2005

In this study, SAM (self-assembled monolayer) was applied as an anti-adhesion layer in the nano molding process, to reduce the surface energy between the nano-stamper and the moldeded polymeric nano patterns. Before depositing SAM on the stamper, the nickel stamper was pretreated to remove oxide on the nickel stamper surface. Then, using the solution deposition method, alkanethiol SAM as an anti-adhesion layer was deposited on nickel surface. To examine the effectiveness of the SAM deposition on the metallic nano stamper, the contact angle and the lateral friction force were measured at the actual processing temperature and pressure for the case of nano compression molding and at the actual UV dose for the case of nano UV molding. The surface energy due to SAM deposition on the nickel nano stamper markedly decreased and the high hydrophobic quality of SAM on the nickel stamper maintained under the actual molding environments.

• Transactions of Materials Processing
• /
• v.20 no.1
• /
• pp.23-28
• /
• 2011

For the fabrication of nano patterned products manufacturing a nano patterned mold is needed in advance. The nano patterned stamper was fabricated by electroforming the AAO master with nickel. The surface of nickel-plated stamper had nano-patterned holes with the diameter of 73 nm and the depth of 83 nm. Hot embossing was used for forming P3HT sheet and the process factors of hot embossing were closer as pressure, temperature and time. In the present paper hot embossing experiments were performed to find the main process conditions to affect the replication ratio of nano patterns on surface of P3HT sheet. As a result, main contributing factors for the replication ratio of hot embossed pattern could be sequentially enumerated as pressure, temperature and time.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.10a
• /
• pp.367-370
• /
• 2003

In this study, application of SAM (self-assembled monolayer) to nano replication process as an anti-adhesion layer was presented to reduce the surface energy between the nano mold and the replicated polymeric nano patterns. The electron beam lithography was used for master nano patterns and the electorforming process was used to fabricate the nickel nano stamper. Alkanethiol SAM as an anti-adhesion layer was deposited on metallic nano stamper using solution deposition method. To analyze wettability and adhesion force of SAM, contact angle and LFM (Lateral Force Microscopy) were measured at the actual processing temperature and pressure for the case of nano compression molding and at the actual UV dose for the case of nano UV molding. It was found that the surface energy due to SAM deposition on the nickel nano stamper markedly decreased and the quality of SAM on the nickel stamper maintained under the actual molding environments.

• Transactions of the Society of Information Storage Systems
• /
• v.1 no.2
• /
• pp.192-196
• /
• 2005

In this paper, we investigated the possibility of replicating patterned media by nano-injection molding process with a metallic nano-stamper. The original nano-master was fabricated by E-beam lithography and ICP etching process. The metallic nano-stamper was fabricated using a nanoimprint lithography and nano-electroforming process. The nano-patterned substrate was replicated using a nano-injection molding process without additional etching process. In nano-injection molding process, since the solidified layer, generated during the polymer filling, deteriorates transcribability of nano patterns by preventing the polymer melt from filling the nano cavities, an injection-mold system was constructed to actively control the stamper surface temperature using MEMS heater and sensors. The replicated polymeric patterns using nano-injection molding process were as small as 50 nm in diameter, 150 nm in pitch, and 50 nm in depth. The replicated polymeric patterns can be applied to high density patterned media.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.9 s.186
• /
• pp.174-178
• /
• 2006

Pyramid shape of micro pattern is applied to the light guide panel (LGP) to enhance the uniformity of the brightness of the LCD. The micro pyramids are molded in intaglio on the surface of the LGP. The size of each pyramid is 5$\mu$m $\times$ 5$\mu$m on bottom and the height is about 3.5$\mu$m. The pyramids are distributed on the LGP surface randomly to be sparser where the light comes in and denser at the opposite side as a result of a simulation using lightools$^{TM}$ Based on this design, a silicon pattern master and a nickel stamper are fabricated by MEMS process and electro plating process. Intaglio micro pyramids are fabricated on the 6' of silicon wafer from the anisotropic etching using KOH and the process time, temperature of the KOH solution, etc are optimized to obtain precise shape of the pattern. A Wi stamper is fabricated from this pattern master by electro plating process and the embossed pyramid patterns turns out to be well defined on the stamper. Adopting this stamper to the mold base with two cavities, 1.8' and 3.6' LGPs are injection molded.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.989-992
• /
• 2004

A new method is proposed to fabricate a reusable qualtz master with order of 100 nm dot pattern on its surface. Some fabrication conditions such as dose are investigated to find optimal condition. This reusable qualtz master is used directly as a stamper to injection mold the dot patterns. Polycarbonate and Polyoxymethylene are used as molding materials and the effect of the mold temperature is also investigated to see the moldabilty of the injection molding for very fine dot features.

• Transactions of Materials Processing
• /
• v.16 no.1 s.91
• /
• pp.9-14
• /
• 2007

In this paper, a mold temperature control method for injection molding is proposed. The inner surface of mold is locally heated by jet impingement to improve pattern transcription. Heating by hot jet is completed while the mold is open. An experimental system that realizes the proposed idea has been built, which includes mold, nozzle assembly and heater. Actual injection molding process including the proposed heating procedure has been conducted to verify the validity of the method. The process has been done for several conditions with different jet temperatures and duration of heating. The results from different conditions are compared.